The problem of alcohol use in aviation remains a serious concern. A significant number of aircraft accidents have been found to be alcohol related and many other not so identified may indeed have had alcohol involvement. While the dangers of piloting an aircraft while intoxicated are obvious, there is relatively little data available regarding the effects of low (<.04%) blood alcohol levels on pilot performance. This research program focuses on the investigation of such effects and the conditions under which pilot impairment is found. Another objective is the dissemination of the information obtained to both the scientific and aviation communities. Prior work on this project using a computer interfaced flight simulator has demonstrated that a blood alcohol concentration (BAC) in the .04-.045% range can affect flight tasks primarily in terms of the pilot's reduced ability to divide attention. A subsequent series of studies have shown that instrument rated pilots can perform a number of instrument flight tasks with BACs below .04%, but at a cost of greater effort and perceived workload on the part of a majority of pilots. Significant alcohol effects were most likely to be found under high cognitive load situations in such situations. Research planned will extend these simulator studies to visual flight rule situations in busy traffic areas where pilots have heavy task loads and maintaining geographical awareness is difficult. A second area of investigation concerns the effect of alcohol on pilots' threshold for, and adaptation to, the perception of angular motion and susceptibility to the vestibular Coriolis effect. An enclosed rotating simulator with instruments and controls interfaced to a computer will be used to investigate the possibility that low alcohol levels may show much greater effects on pilot performance when somatogyral and Coriolis effects occur during angular motion. This situation will also be used to investigate possible persisting hangover effects after the individual's blood alcohol level reaches zero. A final component of the program involves further national-sample based surveys of professional pilots, which will be concerned with both personal and job related factors that increase the probability of alcohol abuse in the aviation environment.